Puffed pet treat with crunchy texture

ABSTRACT

An animal protein-based dog treat has a soft crunch and a stable shelf life without use of an appreciable amount of sodium or chemical preservatives. A method of producing the dog treat entails use of extrusion and heating processes to trap moisture in the interior of the dog treat, and then to expand and evaporate the moisture. This process creates in an internal portion of the dog treat voids or air pockets that provide desired texture and strength characteristics.

RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.12/557,237, filed Sep. 10, 2009, now U.S. Pat. No. 8,496,985, whichclaims benefit of U.S. Provisional Patent Application No. 61/095,895,filed Sep. 10, 2008.

TECHNICAL FIELD

This disclosure relates generally to pet treats and more particularly toprotein-based dog treats.

BACKGROUND INFORMATION

Known dog treats produced from animal protein (e.g., muscle) have anumber of shortcomings. For example, due to stability standards basedupon water activity, known dog treats produced from animal protein aretypically preserved with salt or other chemicals. Dog treats preservedwith salt and/or chemicals are relatively unhealthy; and consumeracceptance of these dog treats is relatively low compared to allnatural, low salt shelf stable snacks made from animal protein. However,low salt, protein-based dog treats are typically very hard and requireapplication of a considerable bite force by a pet to crush and ingestthe treat. Hard dog treats usually include a relatively high caloriccontent, thus rendering such treats inappropriate for use as a pettraining aid because the caloric intake over the course of a trainingsession may be too high and the treats may be too hard.

SUMMARY OF THE DISCLOSURE

One embodiment of the disclosed pet treat is made from a mixtureincluding a base recipe of protein, starch, and water. The pet treatincludes an interior portion having an air pocket structure developedfrom water vapor that forms and expands during a drying process. The airpocket structure provides the pet treat with a density and a compressivestrength that are appreciably less than the density and compressivestrength of a pet treat having no internal air pocket structure. The airpocket structure also provides a puffed form for the pet treat. The pettreat includes an outer surface that substantially encloses the interiorportion and is substantially free from air pockets.

Additional aspects and advantages will be apparent from the followingdetailed description of preferred embodiments, which proceeds withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of a process for producing a dog treat accordingto one embodiment.

FIG. 2 is an isometric view of a segment of an extruded mixture,according to one embodiment, before the segment is baked to form apuffed dog treat.

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2.

FIG. 4 is an isometric view of the extruded mixture segment of FIG. 2after it is heated to form a puffed dog treat.

FIG. 5 is a sectional view taken along lines 5-5 of FIG. 4 to show anair pocket and open structure formed inside the puffed dog treat.

FIG. 6 is a fragmentary isometric view of a Milk-Bone® dog biscuit of atype intended for small dogs weighing less than 20 pounds.

FIG. 7 is a fragmentary isometric view of an Original Alaskan Bear®gourmet dog treat.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Overview

With reference to the above-listed drawings, this section describesparticular embodiments and their detailed construction and operation.The embodiments described herein are set forth by way of illustrationonly and not limitation. Skilled persons will recognize in light of theteachings herein that there is a range of equivalents to the exampleembodiments described herein. Most notably, other embodiments arepossible, variations can be made to the embodiments described herein,and there may be equivalents to the components, parts, or steps thatmake up the described embodiments. For example, although the embodimentsdescribed below pertain to dog treats, the disclosed embodiments may beequally applicable to food items for other animals.

For the sake of clarity and conciseness, certain aspects of componentsor steps of certain embodiments are presented without undue detail wheresuch detail would be apparent to skilled persons in light of theteachings herein and/or where such detail would obfuscate anunderstanding of more pertinent aspects of the embodiments.

According to one embodiment, a method of producing a puffed dog treatentails use of extrusion and heating processes to trap moisture in theinterior of the dog treat, and then to expand and evaporate themoisture. This process creates in an interior portion of the dog treatvoids or air pockets that provide desired texture and strengthcharacteristics.

For example, puffed dog treats are made by providing an extrusionapparatus in which a mixture including protein, starch, and water iscontained. The extrusion apparatus includes an opening from which themixture is to be extruded, and the mixture is forced out of the openingto from a shaped extrudate. The shaped extrudate is cut into multiplesegments, and each of them includes an interior portion and an outersurface substantially enclosing the interior portion. The outersurfaces, which are skin-like in that they have a tensile strengthgreater than the tensile strength of the interior portions, are formedas the mixture passes through the opening of the extrusion apparatus.Moreover, the outer surfaces are hardened as the segments are heated ordried as described in greater detail below. Also, air drying of theouter surfaces that occurs after the mixture is extruded but before thesegments are heated contributes to toughening of the outer surfaces. Theinterior portions include moisture that is trapped due to the skin-likeouter surfaces, making the segments small pressure vessels.

The segments are heated at a temperature that causes the outer surfacesto harden (e.g., case hardening) and the moisture of the interiorportions to transform to vapor (e.g., steam). The outer surfaces act asmoisture barriers so that an appreciable amount of the vapor is retainedwithin the segments while the vapor expands to thereby form air pocketsand air cavities in the interior portions and cause the segments toexpand or “puff up.” The expansion of the segments creates puffed dogtreats that have a soft crunch.

Production Method

FIG. 1 is a flow chart depicting a method 100 of producing dog treatsaccording to one embodiment. First, dry ingredients for the dog treatsare mixed together (step 102). Any known mixing device may be used tomix the dry ingredients. The dry ingredients include dry protein andstarch. The protein preferably is dry muscle protein from one or moretypes of animals. For example, fish, poultry, mammal meat, or acombination thereof may be used. The starch is preferably potato starchsuch as modified potato starch, unmodified potato starch, or acombination of modified and unmodified potato starch. The dryingredients may also include one or more dry nutritional supplementsand/or flavor enhancers (e.g., palatants). For example, dry nutritionalsupplements may include dried fruits, vitamins, amino acids, probiotics,prebiotics, and minerals. The dry ingredients are mixed and blended,preferably at room temperature, until a uniform blend is achieved. Theconsistency of the dry ingredients at this stage is similar to that ofdry ingredients for bread, cookies, or cake.

FIG. 1 shows two alternative processes—a hot extrusion process and acold extrusion process—that may be implemented in the method 100 afterthe dry ingredients are mixed. In the hot extrusion process, the dryingredients are introduced into an extruder (step 104 a). Wetingredients such as water, liquid nutritional supplements (e.g., oilsand liquid forms of fruits, vitamins, amino acids, probiotics,prebiotics, and minerals) may also be introduced into the extruder withthe dry ingredients. The extruder may be any type of known hot extruder(e.g., single or twin screw extruder) used for making food items. Forexample, the extruder may be a Coperion 26 millimeter (mm) twin screwextruder available from Coperion Group, GmbH of Stuttgart, Germany, ahot extruder available from Clextral, Inc. of Tampa, Fla., a hotextruder available from Wenger Manufacturing, Inc. of Sabetha, Kans., ora hot extruder available from Bühler AG of Uzwil, Switzerland. After thedry ingredients (and liquid nutritional supplements, if any) areintroduced into the extruder, water is added and the extruder folds,kneads, and mixes the dry ingredients and water to make a wet ingredientblend or mixture (step 106 a). The folding and mixing action is achievedby high shear and heat zones of the hot extruder machine design. Anamount of water is added so that the mixture has a moisture contentranging from about 20% by weight to about 50% by weight, preferably fromabout 32% by weight to about 40% by weight.

In the cold extrusion process, the wet ingredients (e.g., water andliquid nutritional supplements) are added to and mixed with the dryingredients to form a mixture (step 104 b) before the dry ingredientsare introduced into an extruder. The mixture is then introduced into theextruder (step 106 b). The extruder may be any type of known coldextruder used for making food items. For example, the cold extruder maybe a single screw extruder or may include a positive displacement pump.For example, a cold extruder available from Coperion Group, GmbH;Clextral, Inc.; Wenger Manufacturing, Inc.; or Bühler AG may be used.

In the hot and cold extrusion processes, the mixture is forced out of anopening of the extruder to form a shaped extrudate (step 108). Theextruder includes a die plate, nozzle, or tubing having stationary wallsdefining an opening from which the mixture is extruded. For example, theextruder forces (e.g., pumps) the mixture through a straight,smooth-walled die or tubing having an opening of predetermineddimensions. The opening of the die plate, nozzle, or tubing may be ofany shape such as rectangular, circular, square, triangular, elliptical,or irregular shape. For example, the opening may be of generallyrectangular shape with rounded corners and may include dimensions ofabout 0.63 centimeter (cm) by about 1.5 cm with a radius of about 0.32cm at the corners. The side walls of the opening may be about 0.19 cm inlength. As the mixture is forced out of the opening, the mixture isshaped according to the shape of the opening, and the mixture developsan outer surface that has characteristics different from those of aninterior portion of the shaped mixture. For example, the outer surfaceof the shaped mixture has a tensile strength greater than that of theinterior portion. In other words, a skin-like surface is formed on theoutside of the mixture when the mixture is forced out of the opening.The outer surface forms as a result of compressing and burnishing theouter surface as the extrudate passes along the stationary walls of thedie plate, nozzle, or tubing. The outer surface of the mixture issmoothed and compressed (e.g., burnished) as the mixture contacts thestationary walls when it is being forced out of the opening. Moreover, acontributing factor to denser and higher strength characteristics of theskin-like outer surface is a heating/drying process described below. Asthe mixture is extruded out of the opening, the mixture may tend toexpand so that the shaped mixture has cross-sectional dimensionsslightly greater than the dimensions of the opening. For example, thecross-sectional dimensions of the mixture after extrusion may be about 1cm by about 1.9 cm. Expansion of the extrudate is caused by a number ofdifferent factors. For example, during extrusion, the moisture maybecome hot and start to turn to expanding water vapor. Moreover,hydration and heating of the starch in the mixture causes expansion. Theextrusion process binds and holds the extrudate together. As theextrudate air dries before a drying process described below, the crosssectional dimensions of the extrudate may reduce to about 0.76 cm byabout 1.65 cm. The compressive strength of the extrudate before thedrying process is in a range from about 113 grams (g) to about 170 g.

After the mixture is extruded from the opening, the mixture is cut by acutting device (e.g., knife) into multiple segments (e.g., pellets),each segment corresponding to an individual dog treat (step 110). Whenthe mixture is cut, an outer surface as described above also forms onthe cut ends of the segments from cutting (e.g., shearing) action of thecutting device; the cutting device burnishes each end. Thus, the outersurface of the segments substantially encloses the interior portion.FIG. 2 is a three-dimensional view of an extruded segment 200 accordingto one example. Segment 200 is rectangular-shaped with rounded edges andincludes an outer surface 202 on its six sides 204, 206, 208, 210, 212,and 214. FIG. 3 is a cross-sectional view of segment 200. FIG. 3 showsouter surface 202 surrounding an interior portion 304. Interior portion304 includes moisture from the wet ingredients, and outer surface 202substantially retains the moisture in interior portion 304. Nominaldimensions of segment 200 are a length 216 of about 2.54 cm, a width 218of about 1.65 cm, and a height (i.e., thickness) 220 of about 0.76 cm(measured at approximately the center of segment 200).

After the mixture is cut into segments 200, they are dried according toa drying process. The drying process includes a first heating step 112in which the segments are placed in a heating device (e.g., oven) andheated using infrared radiation, microwave radiation, radio frequencyradiation, direct hot air, direct flame, steam, an electric heat source,or another type of heat source. Segments 200 are heated at a temperaturethat is approximately at or above the boiling point of water. Forexample, the temperature inside the oven may be approximately 148.9degrees Celsius (° C.). First heating step 112 last approximately threeto six minutes. First heating step 112 allows two things to happen—outersurface hardening, and segment expansion or “puffing.” For example, assegments 200 heat up, their outer surfaces dry and harden and therebyincrease in tensile strength, such that the moisture in interiorportions 304 is substantially trapped and not allowed to escape fromsegments 200. Additionally, as segments 200 continue to heat up, themoisture in interior portions 304 transforms to expanding vapor, apositive pressure builds in interior portions 304, and segments 200expand and grow in cross-section to become puffed dog treats 400 (FIG.4) in which air pockets are formed in interior portions 304.

In other words, during first heating step 112, the applied heattransforms the moisture to rapidly expanding vapor. The heat sourcequickly heats up segments 200 so that the vapor in them expands fasterthan it can migrate through outer surfaces 202 allowing segments 200 topuff and expand. Outer surfaces 202 of segments 200 act as moisturebarriers that tend to retain the expanding vapor in interior portions304 of segments 200 before the expanding vapor can migrate out of themby evaporation. The expanding vapor produces air pockets or air voids ininterior portion 304 of segments 200 and causes them to expand or “puffup.” The starch of segments 200 may also contribute to expansion andhelp to make segments 200 pliable to stretch and expand so that voids orair pockets can be formed. Although interior portions 304 include airpockets, outer surfaces 202 of segments 200 remain substantially freefrom holes or air pockets caused by expanding vapor. However, surfacecracking (similar to cracking that occurs on the outside of a loaf ofbread when it is being baked) may occur.

As described above, first heating step 112 hardens outer surfaces 202.Compressive strength tests were performed on two groups of puffed dogtreats 400—a first group of 10 puffed dog treats 400 with their outersurfaces 202 removed, and a second group of 10 puffed pet treats 400with their outer surfaces 202 intact. A sander, small files, and anEtalon dial caliper were used to remove an outside layer ofapproximately 0.12 cm to approximately 0.15 cm thick from the firstgroup of puffed pet treats 400. A compression test device (e.g., aspring tester operable to apply a force having a magnitude between about0 kilograms (kgs.) and about 56.7 kgs. available from Rimac Tools, Inc.of Dumont, N.J.) was used to conduct tests to measure the compressivestrength of the first and second groups of puffed dog treats 400. Duringthe tests, the average magnitude of force required to cause breakage ofthe first group of puffed dog treats 400 was about 4.99 kgs. (11 lbs.),and the average magnitude of force required to cause breakage of thesecond group of puffed dog treats 400 was about 7.94 kgs. (17.5 lbs.),which is about 2.95 kgs. (6.5 lbs.) more than the average of the firstgroup.

Although first heating step 112 causes segments 200 to expand producingpuffed dog treats, the drying process also includes a second heatingstep 114 to bring the moisture content and water activity of segments200 to a desired level. For example, the moisture content of segments200 after second heating step 114 may be in the range from about 2% orless by weight to about 8% by weight. Second heating step 114 may be acontinuation of first heating step 112 in which the heating device usedduring first heating step 112 is used for second heating step 114 andthe temperature inside heating device is maintained at approximately thesame temperature that was used during first heating step 112.Alternatively, the temperature used during second heating step 114 maybe different from that used during first heating step 112. For example,the temperature inside the heating device may be adjusted, or segments200 may be transferred to a second heating device that has a differenttemperature. The temperature during second heating step 114 may be in arange from about 135° C. to about 149° C. Second heating step 114 lastsapproximately 90 minutes. After second heating step 114, segments 200are cooled (step 116).

Method 100 produces puffed dog treats having a soft crunch; the puffeddog treats are easy for a pet to chew and ingest. For example, method100 may produce pillow-shaped pet treats with a hardened outer surfaceand a crunchy interior portion having an air pocket structure. The airpocket structure makes the puffed dog treats less dense than theyotherwise would be without the air pocket structure. Moreover, acompressive strength of a puffed dog treat is appreciably less than itwould otherwise be absent the air pocket inner core or inner structure.For example, using a compression test device available from Rimac Tools,Inc., tests were conducted to measure the compressive strength of driedpuffed dog treats 400 and dried segments 200 that were not puffed.During the tests, the magnitude of force required to cause breakage ofpuffed dog treats 400 ranged from about 3.0 kgs. (6.6 lbs.) to about11.3 kgs. (25 lbs.) compared to about 27.2 kgs. (60 lbs.) to about 40.8kgs. (90 lbs.) for dried non-puffed segments 200. Puffed dog treats 400have a stable shelf life without having an appreciable amount ofsodium-based or chemical preservatives. For example, puffed dog treats400 may have less than 0.01% by weight of a sodium-based or chemicalpreservative.

FIG. 4 is a three-dimensional view of puffed dog treat 400 after beingheated and cooled according to method 100. FIG. 4 shows that treat 400has a convex or “puffed up” surface profile. FIG. 5 is a cross-sectionalview of treat 400 and shows hardened outer surface 202 and multipleinternal air pockets 503 formed in interior portion 304 during firstheating step 112. A substantial portion of the volume of puffed dogtreat 400 may be in the form of air pockets 503. For example, the volumeoccupied by air pockets 503 may be from about 20% to about 70% of thevolume of puffed dog treat 400. After heating, nominal dimensions oftreat 400 are a length 402 of about 2.54 cm, a width 404 of about 1.52cm, and a height (i.e., thickness) 406 of about 1.27 cm (measured atapproximately the center of treat 400). Height 406 of treat 400 aftersteps 112, 114, and 116 is about 1.7 times height 220 of extrudedsegment 200. The volume occupied by treat 400 is greater than the volumeoccupied by extruded segment 200. For example, the volume of extrudedsegment 200 is about 3.18 cm³, and the volume of treat 400 is about 4.9cm³. In other words, the volume occupied by the air pockets (i.e., the“void volume”) of treat 400 is about 1.72 cm³, which is about 54% of thevolume of extruded segment 200 and about 35% of the volume of treat 400.

Example Production Run

The following is an example of a production run for making puffed dogtreats 400. To make a batch of puffed dog treats 400, the following dryingredients were mixed in a mixing bowl using a Leland ribbon mixer: 25kgs. (55.1 lbs.) of dry salmon, 11.3 kgs. (25 lbs.) of PC-10 modifiedpotato starch, 1.3 kgs. (3 lbs.) of sweet potato, 0.9 kg. (2 lbs.) ofdried blueberry, 0.9 kg. (2 lbs.) of dried cranberry, 0.01 kg. (0.03lb.) zinc, and 0.009 kg. (0.20 lb.) Naturox® Plus Dry antioxidant. Thedry ingredients were mixed together for 2.5 minutes, the sides of themixing bowl were scraped, and the dry ingredients were mixed for anadditional 2.5 minutes. After mixing, the dry ingredients resembled thedry ingredients of a cookie or cake batter.

The dry ingredients were fed into a Coperion 26 mm twin screw extruderat a rate of 0.45 kg. (16.0 ounces (oz.)) per minute with a screw speedof about 375 revolutions per minute (rpm). Water was added to the dryingredients at a rate of approximately 0.23 kg. (8.25 oz. by weight) perminute during the extrusion process. The extruder mixed the water anddry ingredients in the heated screw chambers. The heat chambers were setto different temperatures as follows: chamber #1=0° C., chamber #2=15°C., chamber #3=15° C., chamber #4=15° C., chamber #5=90° C., chamber#6=90° C., chamber #7=15° C., chamber #8=15° C., chamber #9=15° C.,chamber #10=90° C., chamber #11=90° C., and chamber #12=90° C. Themixing and kneading action of the twin screws and the heat in each ofthe chambers caused the starch to bind with the other ingredients. Thescrews of the extruder forced the mixture through an opening in a dieplate or nozzle, and the extruded mixture was cut (e.g., sheared) intomultiple segments 200 of a desired length.

Segments 200 were baked in an oven available from Enviro-Pak Corporationof Clackamas, Oreg., at a temperature of approximately 148.9° C. forapproximately 90 minutes. The temperature of the oven generated vaporinside segments 200 and caused the vapor to expand while remainingtrapped inside them thereby causing segments 200 to “puff up.” Segments200 thus attained an expanded appearance with their centers filled withair pockets. Segments 200 were relatively light in density yet firm suchthat a dog consuming them would experience a soft crunch.

Compressive strength testing was performed on puffed dog treats 400produced during the production run, and comparison compressive strengthtesting was performed on a Milk-Bone® small dog biscuit 600 (shown inFIG. 6) and an Original Alaskan Bear® treat 700 (shown in FIG. 7).Compressive strength testing was performed on 20 puffed dog treats 400,20 Milk-Bone® small dog biscuits 600, and 20 Original Alaskan Bear®treats 700 using a spring tester available from Rimac Tools, Inc. thatwas modified to check the compressive strengths of them. The springtester was operable to apply a force having a magnitude from about 0kgs. to about 56.7 kgs. (125 lbs.). The average magnitude of forcerequired to break (e.g., split into pieces) the 20 puffed dog treats400, 20 Milk-Bone® small dog biscuits 600, and 20 Original Alaskan Bear®treats 700 was as follows:

Puffed dog treats 400: 7.94 kgs. (17.5 lbs.) average

Milk-Bone® small dog biscuits 600: 42.6 kgs. (94 lbs.) average

Original Alaskan Bear® treats 700: 15.7 kgs. (34.6 lbs.) average.

Thus, the force required to break puffed dog treats 400 was considerablyless than that required to break Milk-Bone® biscuits 600 and OriginalAlaskan Bear® treats 700, demonstrating that puffed dog treats 400provide a softer chew for a pet.

Skilled persons will recognize that many variations, enhancements, andmodifications of the concepts described herein are possible withoutdeparting from the underlying principles of the invention. The scope ofthe invention should, therefore, be determined only by the followingclaims and their equivalents.

1. A pet treat, comprising: a puffed segment made from a mixtureincluding protein, starch, and liquid, the puffed segment having anair-containing interior portion with air pockets and a hardened outersurface substantially enclosing the air-containing interior portion, theair-containing interior portion of the puffed segment characterized by avoid volume occupied by the air pockets and an amount of moisture ofless than about 8% by weight in the air-containing interior portion toprovide the puffed segment with a crunchy texture and a soft chew for ananimal consuming the pet treat.
 2. The pet treat of claim 1, in whichthe puffed segment is characterized by a compressive strength, and inwhich no greater than about 15.5 kilograms of force applied to a portionof the hardened outer surface is needed to overcome the compressivestrength to achieve breakage of the puffed segment.
 3. The pet treat ofclaim 1, in which the protein includes animal protein.
 4. The pet treatof claim 3, in which the animal protein includes salmon.
 5. The pettreat of claim 1, in which the starch includes potato starch.
 6. The pettreat of claim 1, further comprising a nutritional supplement.
 7. Thepet treat of claim 6, further comprising a fruit supplement.
 8. The pettreat of claim 6, further comprising a mineral supplement.
 9. The pettreat of claim 6, further comprising a probiotic supplement.
 10. The pettreat of claim 6, further comprising an amino acid supplement.
 11. Thepet treat of claim 6, further comprising a vitamin supplement.
 12. Thepet treat of claim 1, further comprising a sodium-based or chemicalpreservative of less than 0.01% by weight.
 13. The pet treat of claim 1,in which the puffed segment is characterized by a volume, and in whichthe void volume occupies from about 20% to about 70% of the volume ofthe puffed segment.